REDUCTIMETRIC DETERMINATION OF SOME QUINONES WITH IRON(II)

A simple and convenient reductimetric titration method has been develo ped for the determination of some quinones using iron(II) as a reducta nt in buffer medium (optimum pH 4.0-5.0) in the presence of oxalate io ns (optimum concentration 0.06-0.12 M). The end-point can be determine d either potentiometrically or visually using some oxazine dyes as ind icator. In these titrations, the quinones as well as the indicators ar e reduced in a two-electron reduction step to their corresponding hydr oquinones and leuco-bases respectively. The function of pH and oxalate ions in the reaction medium has also been discussed.